Catalytic hydrogenation of esters of aliphatic carboxylic acids



Pat'ented Sept. 14, 1937 um'rgo STATESfPAT CATALYTIC HYDROGENATION OF ESTER OF ALIPHATIC CABBOXYLIC ACIDS om Schmidt, Ludwigshafen-on-the-Rhine, Germany, assignor to I. G. Farbenindustrie Aktiengesellschaft, Frankfort-on-theeMain, Germany No Drawing. Appllcation March c, 1930, Serial No. 433,840. In Germany November 20, 1925 11 Claims. (oi. 260-156) The present invention relates to'the catalytic hydrogenation of esters of carboxylic acids.

I have found that the latent carboxylic group tained by a very fine disintegration of the catalytic substances which effect may be obtained for example by depositing the catalytic substances on finely divided substrate, such as fibrousasbes- 15 tos, graphite, silica gel or metal powders and the a like, and/or by adding to the catalytic substances activating substances. Suitable catalytic substances are for example copper, nickel, silver,

zinc, cadmium, lead or cobalt or mixtures thereof and they may be prepared from their salts, oxides or other compounds prior to or after an incorporation with activating substances. The acti vating substances may be chosen from compounds of the metals giving acids with oxygen, such as chromium, molybdenum, tungsten, uranium, manganese, vanadium or titanium 'or mixtures thereof as well as from compounds of the alkali, alkali earth or rare earth metals. As examples ofsuch metals and of other metals may be men- 30 tioned potassium, sodium, calcium or magnesium, niobium, tantalum, thorium, cerium, zirconium, rubidium, cesium, osmium, palladium or tantalum or several of these compounds or from boron. The metals giving acids with oxygen may be employed in the form of the alkali metal or alkaline earth metal salts of the said acids or in the form of the salts with the hydrogenating metals as for example copper, nickel, silver or zinc vanadates,'molybdates, tungstates and the like and 40 in this case the said hydrogenating metals must not be present as such.' The compounds of the rare metals such as oxides or their compounds with the aforesaid acids may be also mixed with the-compounds of the acid forming metals.- The 45 order of mixing the aforesaid single components is not important and, as already stated, the activating substances may be mixed with compounds of the hydrogenating metals, whereupon the whole mass is subjected to a treatment with hydrogen, 50 whereby the compounds of the hydrogenating metals are converted wholly or at least partially into the free metals. Otherwise the components may be mixed for example in a melt of the activating substances to which the hydrogenatin 55 metals or their compounds are added.

Eur oFFIcE];

The temperatures employed depend generally on the nature of the ester under treatment and its volatility; generally temperatures between about 200 and 400 C. are employed. The quantity of hydrogen is advantageously chosen considerably above that theoretically required for the hydrogenation and in the place of pure hydrogen gaseous, mixtures containing the same may I be employed. In this manner esters of monobasic carboxylic acids can bewaltalytically hydrogenated with the formation of aldehydes, alcohols and even of hydrocarbons depending on the conditions of-working, the acid component of the esters being apparently converted at first into an aldehyde and subsequently into an alcohol and finally into a hydrocarbon. Thus, for example by applying a rather high temperature and a rather low quantity of hydrogen aldehydes may be produced, whereas the application of low temperatures and of higher quantities of hydrogen leads to the production of alcohols; by choosing 'very strong conditions of working hydrocarbons are obtained. In this manner even esters of vegetal carboxylicacids, having a very high molecular weight, such as oleic methyl ester, oleic acid or train oil acid or linoleic acid ethyl esters can be converted into alcoholsof the aliphatic series having a high molecular weight which hitherto have not been available commercially. These alcohols may find useful application in the production, for example of artificial waxes or cosmetic' preparations or of washing. emulsifying or wetting agents by sulphonation, for which purposes they may, be employed even in acid baths ortogether with hard water.

.By the addition as carriers of metal oxides having a basic reaction, such as magnesia, of agents assisting in splitting 01! water, such as alumina, catalytic substances can be obtained generally allow of obtaining a very farparticularly energetic hydrogenation alres, whereas the addition of acid agents, such as precipitated silicic acid allows-of stopping the hydrogenation at'any desired intermediate stage. Also the nature of the metal contained in the catalytic substances allows of influencing the reaction in a considerable degree. Thus, for example, nickel provides in many .cases a much more energetic hydrogenation than copperv and the catalytic substances rongly activated are in many efiicient than catalytic sub- 01 finelydividedmetals solely.

amples will rub er illustrate ready at low temperatu which have been st cases much more stances consisting The following ex tice, but the invention is not limited thereto.

Example 1- 1 liter each of glass beads of about 7 millimeters diameter is moistened with a saturated aqueous solution 01' 3.3 grams of ammonium about 160 times per hour with fresh initial mater rial, whereby about 50 per cent 01' the acetic acid contained in the acetic ester is converted into ethyl alcohol. By repeatedly leading the reaction mixture over the catalytic mass the yield of alcohol can be further increased.- The gaseous mixture leaving the reaction vessel is cooled, the mixture of alcohol and acetic ester being then separated in any usual and convenient manner. The yield of ethyl alcohol may be increased to about per cent of that theoretically obtainable.

Example 2 1. liter each of glass beads of about 7 millimeters diameter is stirred with- 300 cubic centimeters each of a 4 per cent aqueous colloidal solution of silicic acid and with grams each of finely powdered copper chromate. The mass is then dried and treated with hydrogen at a temperature of from 270 to 280 C. A mixture of 100 parts by volume 01' hydrogen and 0.2 part by volume of the ethyl esters .of train oil acid obtainable by heating train 011 with ethyl alcohol to a temperature above 100 C., is then passed at from 280 to 290 C. over the aforesaid catalytic mass and the gaseous mixture leaving the reaction vessel is cooled, whereby solid crystalline products are obtained which may be purified by dissolution in ethyl alcohol or acetone and recrystallization. A good yield of octodecyl alcohol having a melting point of 56 to 60 C. is obtained.

- Example 3 ized glycollic ethyl ester is passed over the catalytic mass in such a manner that the reaction space is fed about 70 times per hour with fresh initial material. The gaseous mixture leaving the reaction vessel is cooled as far as possible, whereby ethyl alcohol and ethylene glycol are obtainedtogether with small quantities of water and unaltered initial glycollic ester, the mixture being then separated in any usual and convenient manner, for example by fractional distillation. 4

Example 4 1 liter each of glass beads of about 7, millimeters diameter is stirred with'270 cubic centimeters each of a 4 per cent aqueous colloidal solution of silicic acid, 133 grams each of finely how the invention may be carried out in pracpowdered nickel carbonate and 3.3 grams each.

of ammonium chromate. The mass is then dried and treated with hydrogen at from 300 to 320 C.

A mixture of 100 parts by volume or hydrogen and 0.75 part by volume of vaporized linoleic methyl ester is then passed over the aforesaid catalytic mass at from to'200 C., the gaseous mixture leaving the reaction vessel being cooled. A water-clear liquid is obtained which consists almost exclusively of hydrocarbons (hexadecane and its homologues), the main portion of which boils between 286 and 310 C., higher alcohols being not contained in the product.

The process according to this and. to the foregoing examples may be also carried outwith the esters in the liquid state and/or at superatmospheric pressure.

What I claim is:-

1. The process for the catalytic hydrogenation of esters of aliphatic alkylmonocarboxylic acids, which comprises passing the said esters together with hydrogen while heating to a temperature of the range from 200 to 400 C. over a cobalt catalyst containing an activating substance consisting of an oxide of the metals forming acids with oxygen until substantial quantities of alcohols corresponding to the said alkylmonocarboxylic acid radicles are formed.

2. The process for the catalytic hydrogenation of esters of. aliphatic alkylmonocarboxylic acids, which comprises passing the said esters together with hydrogen while heating to a temperature of therange from 200 to 400 C. over a hydrogenating catalyst essentially comprising cobalt until substantial quantities of alcohols corresponding to the said alkylmonocarboxylic acid radicles are formed.

3. The process forthe catalytic hydrogenation of esters of aliphatic alkylmonocarboxylic acids, which comprises passing the said esters together with hydrogen while heating to a temperature of the range from 200 to 400 C. over an activated hydrogenating catalyst essentially comprising cobalt until substantial quantities of alcohols corresponding to the said alkylmonocarboxylic acid radicles are formed.

4. The process for the catalytic hydrogenation of esters of aliphatic alkylmonocarboxylic acids, which comprises passing the said esters together with hydrogen whileheating to a temperature of the range from 200 to 400 C. over a hydrogenating catalyst essentially comprising cobalt in combination with an activating substance, selected from the class consisting of oxides of metals giving acids with oxygen and compounds of alkali, alkaline earth and rare earth metals with metal acids until substantial quantities of alcohols corresponding to the said alkylmonocarboxylic acid radicles are formed.

5. The process for the catalytic hydrogenation of esters of aliphatic alkylmonocarboxylic acids,

which comprises passing the said esters together with hydrogen while heating to a temperature of the range from 200 to 400 C. over a hydrogenating catalyst essentially comprising cobalt activated by the addition of a basic reacting metal oxide as a carrier until substantial quantities of alcohols corresponding to the said alkylmonocarboxylic acid radicles are formed.

6. The process for the catalytic hydrogenation of esters of aliphatic alkylmonocarboxylic acids, which comprises passing the said esters together with hydrogen while heating to a temperature of the-range from 200 to 400 C. over a hydrogenatlng catalyst consisting oi the cobalt salt of a metal acid until substantial quantities of alcohols corresponding to the said alkylmonocarboxylic acid radicles are formed. a

'7. The process for the catalytic hydrogenation of esters of aliphatic alkylmonocarboxylic acids, which comprises passing the said esters together with hydrogen while heating to a temperature of the range from 200 to 400 C. over a hydrogenating catalyst essentially comprising cobalt activated by the addition of a compound selected from the group consisting of salts of metal acids and basic metal oxides deposited on 'a carrier until substantial quantities of alcohols corresponding to the said alkylmonocarboxylic acid radicles are formed.

8. The process for the catalytic hydrogenation of esters of aliphatic alkylmonocarboxyl ic acids, which comprises passing monoalkyl esters high molecular fatty acids of vegetal origin to- 20 gether with hydrogen while heating to a temperature of the range from 200 to 400 C. over a hydrogenating catalyst essentially comprising cobalt'until substantial quantities of alcohols corresponding to the said alkylmonocarboxylic acid 25 radicles are formed;

9. The process for the catalytic hydrogenation of an organic ester of an aliphatic alkyl carboxylic acid containing at least 8 carbon atoms I in its molecule which comprises heating said ester together with hydrogen at a temperature of about 250 C. at superatmospheric pressure in the presence of a hydrogenating catalyst essentially comprising cobalt as hydrogenating constituent. a

10. The process for the catalytic hydrogenation.

of an organic ester of an aliphatic alkyl carboxylic acid containing at least 8 carbon atoms in its molecule which comprises heating said ester together with hydrogen at a temperature of about 250 C. at superatmospheric pressure in the presence of an activated hydrogenating of esters of aliphatic aikylmonocarboxylic acids,-

which comprises passing vapors of the said esters together with hydrogen while heating to a temperature oi! the range from 200 to 400 C. over an activated hydrogenating catalyst essentially comprising cobalt until substantial quantities of alcohols corresponding to the said alkylmonocarboxylic acid radicles are formed.

OTTO SCHMIDT. 

